If you are suffering from Back pain, it's your abdominal core muscles that you need to build up. There is a group of muscles in your tummy that wrap around your abdomen and spine that give your spine support a bit like a corset. I also suffer with back pain and my back is very stiff and slightly tilted in position which is a real pain when I canter as I have to get in a two point position.
If I were you I would go and see a physio and get some exercises. I suffered in silence and finally went when I was really bad, pain down into my ankle and could hardly move. It took months to get better and I'm still suffering over a year later.
There must be some thing not quite right with your back that is being aggravated it's probably muscular.
Don't do what I did and leave it till its really bad (a thing most people do when they work in the medical profession). Its easier to fix a small problem.